Lightweight class and hbm2java generator

alexandrupopescu · **Posted:** Thu May 12, 2005 7:54 am

Hibernate version: 3.0.3; respectively Hibernate tools as per CVS

Mapping example:

Code:

<hibernate-mapping package="com.ez.ezrt.model">
   <class name="ITDatabaseNL"
         table="ITDATABASE"
         mutable="false"
         batch-size="10">
         <id name="id" 
         type="java.lang.Long" 
         column="ID"
         unsaved-value="0">
      
         <generator class="identity" />
      </id>

      <property name="itName" 
              type="java.lang.String" 
              column="itName"
              not-null="true" 
              unique="true" 
              length="100" />
   </class>
   
   <class name="ITDatabase" 
         table="ITDATABASE"
         mutable="false"
         batch-size="10"
         polymorphism="explicit">
      <meta attribute="extends">ITDatabaseNL</meta>
      
      <id name="id" 
         type="java.lang.Long" 
         column="ID"
         unsaved-value="0">
         <generator class="identity" />
      </id>

      <property name="itName" 
              type="java.lang.String" 
              column="itName"
              not-null="true" 
              unique="true" 
              length="100" />
              
      <property name="connectionURL" 
              type="java.lang.String"
              column="connectionURL" 
              not-null="true" 
              length="100" />
   </class>
</hibernate-mapping>

According to LightweightClass the recommended solution is to use

Code:

polymorphism=explicit

.

I have find the way to specify that ITDatabase extends ITDatabaseNL in the generated code (see the

Code:

<meta>

usage).

However at the 2nd step i wanted to define that the generated fields in the ITDatabaseNL are protected level and so they are not getting regenerated in the ITDatabasa.

Is this possible?

alexandrupopescu · **Posted:** Thu May 12, 2005 8:02 am

I have found the way to generate the field as protected

Code:

but it seems the tool is not considering this when generating the extends class.

max · **Posted:** Thu May 12, 2005 8:36 am

what do you mean ?

it will generate protected fields for all the fields listed at the same level and under it in the xml.

/max

alexandrupopescu · **Posted:** Thu May 12, 2005 9:30 am

In the above case I expect (in fact, to reformulate :-) it would be nice) to have:
[code]
public class com.ez.ezrt.model.ITDatabaseNL {
protected Long id;
[....]

public Long getId() {...}

public void setId() {...}
}

public class com.ez.ezrt.model.ITDatabase extends ITDatabaseNL {
// surprize: in here just the property that is not already defined in the super
}

max · **Posted:** Thu May 12, 2005 10:09 am

hbx-259

alexandrupopescu · **Posted:** Thu May 12, 2005 10:16 am

This HBX-259 is for the other thread ;-).

max · **Posted:** Thu May 12, 2005 10:24 am

well cant hit the right posting each time ,)

...any way....

the meta attribute is just inserted literally - we don't try to be clever and merge stuff (it would be a pain to do correctly)

for that you would need to map it explicitly via inheritance.

...we *might* be able to support it in the future - but as far as i remember there are many common cases which is hard to do reliably.

add a jira for it.

/max

alexandrupopescu · **Posted:** Thu May 12, 2005 11:45 am

I agree with you (on both ideas ;-).

Can you point me to the right direction for using inheritance and the leightweight classes? (it seems i cannot figure out - is it the case of Table per class hierarchy scenario, without using a discrimitator column and respectively a discriminator-value in subclass definition?)